Backup your "personal files".

Go over to microsoft.com and create Windows-10 64bit USB flash-drive with Media Creation Tool.
Clean-install Windows.

I don't use it, but if you really want to troubleshoot Support-Assist, there is a whole Forum section dedicated to it.

https://www.dell.com/community/SupportAssist-for-PCs/bd-p/supportassist-pcs?ref=lithium_menu